Information concerning the nucleotide sequences of the human genome is produced everyday by large-scale sequencing in the human genome project. The final object of the human genome project is not simply to determine the entirety of the nucleotide sequences of the genome, but also to elucidate the constitutional information thereof; that is, information about various human life phenomena from the nucleotide sequence information of DNA. Regions encoding proteins in the human genome sequences account for only a small portion thereof. Currently, prediction of coding regions is being carried out using information science techniques that are referred to as “neural network” and using the hidden Markov model. However, the prediction accuracies of these techniques are not yet sufficient. Even under the current situation, where information concerning the nucleotide sequences of the human genome has been accumulated, coding regions are still being elucidated. Moreover, elucidation of the functions of a protein that is encoded by each coding region is a future object. In the future, for example, it is desired to analyze a gene associated with a specific disease such as carcinoma and to utilize such gene for the detection and treatment of carcinoma.
For example, it has been conventionally reported that N-type sugar chains of glycoproteins are associated with carcinoma. The N-type sugar chains of glycoproteins are involved in various life phenomena, fertilization, generation, immunology, intracellular transport, aging, carcinoma, and the like, so that various pathological conditions are induced by abnormal sugar chains. In particular, high branching of sugar chains is observed in carcinoma cells, indicating their involvement in biological activity such as the metastasis ability of carcinoma cells. The formation of a high-branched sugar chain structure is determined by activation of a specific glycosyltransferase. N-acetylglucosamin transferase is known as an enzyme important in determination of a sugar chain structure. N-acetylglucosamin transferase I and II (GnT-I and -II) are involved in determination of a basic core structure. Each of GnT-III, -IV, -V, and -VI enzymes is involved in transferring N-acetylglucosamin to a particular part of a sugar chain, thus having a large effect on high branching. Furthermore, sialic acid transferase and fucose transferase are enzymes important in determination of the terminal structures of a sugar chain.
Although GnT-III, -IV, -V, and -VI recognize a common substrate, almost no homology was found in the cDNA structures thereof. GnT-III acts to transfer N-acetylglucosamin to a mannose of the core of a N-type binding sugar chain, forming double-branched GIcNAc. GnT-IV and -VI are enzymes involved in biosynthesis of β1-4 chain of N-glycan. GnT-V is an enzyme involved in biosynthesis of β1-6 chain of N-glycan. An example of such an N-acetylglucosamine transferase associated with canceration is GnT-V.
Association of GnT-V with metastasis has been reported (see non-patent document 1 and non-patent document 2). Granovsky et al. have shown that in an experiment using GnT-V-knockout mice, GnT-V is also essential in carcinoma growth in addition to metastasis. Furthermore, Murata et al. have reported correlation between GnT-V and metastasis of colon carcinoma (see non-patent document 3).
Non-patent document 1    Demetriou M et al., J. Cell Biol., 130 (1995), 383
Non-patent document 2    Granovsky et al., Nat. Med., 6 (2000), 306
Non-patent document 3    Murata et al., Clin. Cancer Res., 6 (2000), 1772